This invention relates to new and improved solutions for packaging high-water soft contact lenses and to methods for treating contact lenses with such solutions to improve the comfort of the lenses during wear. In particular, the present invention is directed to contact-lens packing solutions comprising a non-ionic surfactant that is a compound comprising at least about 90 weight percent of poly(oxyethylene) and poly(oxypropylene) segments, in one or more copolymer chains, wherein the weight average molecular weight of said surfactant is from about 4000 to about 30,000 and wherein at least about 40 weight percent of said poly(oxyethylene) and poly(oxypropylene) segments are poly(oxyethylene) segments.
Blister-packs and glass vials are used to individually package each soft contact lens for sale to the customer. Saline or deionized water is commonly used to store the lens in the blister-packs, as mentioned in various patents related to the packaging or manufacturing of contact lenses. Because lens material may tend to stick to itself and to the lens package, packaging solutions for blister-packs have sometimes been formulated to reduce or eliminate lens folding and sticking. For this reason, polyvinyl alcohol (PVA) has been used in contact-lens packaging solutions.
The amphoteric surfactant miranol, disodium cocoamphodiacetate, has been used in a packaging solution for one-day disposable lenses, as disclosed in PCT/GB 96/02937 (GB Appln. No. 9524452.1). This application states that such a surfactant in the contact lens packet provides improved wearer comfort and avoids the inconvenience of purchasing and administering special ocular lubricants, for example, in the form of eye drops. The application, however, provides no evidence of the alleged benefits of using the compound and, for the most part, makers of contact lenses have not used any surfactants in storage solutions for new lenses.
Poloxamine and poloxamers are examples of non-ionic surfactants having one or more poly(oxyalkylene) chains. Poloxamines and poloxamaers are well-known wetting and lubricating agents for contact lenses and have been used in lens wetting drops and in lens-care solutions for treating lenses after use or while in use in the eye. For example, U.S. Pat. No. 4,786,436 and several other patents to Ogunbiyi et al. disclose poloxamine as a wetting agent. Contact-lens rewetting drops containing surfactants such as poloxamine and poloxamer have been used to make contact lens wear more comfortable, to soothe the eyes, and to moisten lenses to minimize dryness. Surfactants such as poloxamine, poloxamer, and tyloxapol have been used in multi-purpose solutions, for cleaning, wetting, and storing lenses.
Certain combinations of poly(oxyalkylene) surfactants have also been disclosed for use in the eye to preventively clean lenses and inhibit deposits. For example, U.S. Pat. No. 5,209,865 (Winterton et al.) discloses the combination of certain poloxamers and poloxamines to maintain clean lenses in the eye.
Work presented by Lyndon Jones at the 1995 BCLA (British Contact Lens Association) Conference has indicated that patients who use a ReNu(copyright) multi-purpose solution for cleaning, storing, and wetting lenses experienced increased comfort with lenses worn over short wearing times of 2-4 weeks when compared to other solutions. ReNu(copyright) solution comprises a borate buffered isotonic solution having several unique aspects, including the combination of a borate buffer, a PHMB disinfecting agent, and a poloxamine surfactant at specified concentrations.
Non-ionic surfactants, including poloxamine and poloxamer compounds, have not been used for wetting fresh or unused lenses. This is probably largely due to the wide-spread belief that tear fluid provides adequate wetting for fresh or unused contact lenses, and that any surfactant on the lens would be quickly displaced in the eye. Fresh lenses in FDA categories Group II or Group IV contain at least fifty percent water content and are expected to be well hydrated when taken from the blister-pack for first use.
It has been stated that if a lens is thoroughly cleaned before insertion, lacrimal fluid can adequately wet the lens. Furthermore, the difficulties of adding a surfactant to a packaging solution, including the possibility of lowering shelf-life and/or adverse reactions during heat sterilization, have further limited the use of surfactants in a packaging solution for the purpose of providing any possible or marginal effect on lens comfort. It is only after a lens has been worn, when proteins or other deposits have formed on the surface of the lens, that surfactants have been used in standard lens-care solutions.
It is highly desirable that contact lens be as comfortable as possible for wearers. Manufacturers of contact lens are continually working to improve the comfort of contact lenses. Nevertheless, many people who wear contact lenses still experience dryness or eye irritation throughout the day and particularly towards the end of the day. An insufficiently wetted lens at any point in time will cause significant discomfort to the lens wearer. Although wetting drops can be used as needed to alleviate such discomfort, it would certainly be desirable if such discomfort did not arise in the first place.